Think back on the last time you saw Kenneth Lonergan’s 2000 film, “You Can Count On Me.” Do you remember how good it was? The intellectual and emotional complexity of the script? Those remarkable performances by Mark Ruffalo and Laura Linney? That scene — to choose one among many — between Terry (Ruffalo) and his 8-year-old nephew, Rudy (Rory Culkin), in which the drunk Terry sits next to Rudy’s bed late at night, smoking a cigarette and telling Rudy why his dad is such a jerk and why the town he lives in sucks so much? (“Fortunately for you, though, your mom is like, the greatest. So you had some bad luck, and you had some good luck.”) It was a modest story of a brother and sister whose parents die when they’re kids and whose lives are blown in different directions and who, years later, come to some almost-peace about what they can and can’t be for each other. But there was such intense realness about it, the way people really talk, the way lives are actually lived, that was unlike anything else on screen, radical almost, in its attention to the genuine messiness of human lives.

You may have wondered why Lonergan never made another movie. Or you may know that he did: a film called “Margaret,” which might be even better than “You Can Count On Me.” The cast included Anna Paquin and Matt Damon and Mark Ruffalo and Matthew Broderick. Among its several credited producers were a couple highly respected Hollywood veterans: Scott Rudin and Sydney Pollack. So when Lonergan began shooting the film in 2005, after taking two years to write the screenplay, “Margaret” had a lot going for it. When it was finally released six years later, in late 2011 — after a brutal and bitter editing process; a failed attempt by no less a cinematic eminence than Martin Scorsese to save the project; and the filing of three lawsuits — several serious film people called it a masterpiece. And almost no one saw it.

Beyond the matter of who breached what agreements, though, the question that has loomed over the film is what happened to Lonergan. How did the guy who wrote and directed “You Can Count On Me” — and who, moreover, has been arguably the most important American playwright of the last 20 years — get so lost in the forest of his own film? And if the process was as acrimonious as it is said to have been, what did that do to him, personally and creatively? How does an artist recover from that? Does he recover at all?

I have not seen “Margaret” but loved “You Can Count on Me.” I plan to watch the director’s cut DVD of “Margaret” this summer.